LSJ
ὁ, a Persian gold coin (but Δ. ἀργύρειοι Plu. Cim. 10), prop. Adj. agreeing with στατήρ (in full, Th. 8.28, Hdt. 7.28), Ar. Ec. 602, X. An. 1.1.9, Herod. 7.122, etc. ; so χρυσὸς χαρακτῆρα Δαρεικὸν ἔχων D.S. 17.66; χρυσὸς Δαρεικός Alciphr. 1.5; — written Δαρικός and Δαριχός, IG 5(1).1 (Sparta). (From Δαρεῖος, cf. Poll. 3.87, acc. to some not D. Nothus, Harp. ; the connection with Bab. dariku (dub.sens.) is v. doubtful.)
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)